This disclosure generally relates to a downhole valve.
Hydrocarbon fluid (oil or gas) typically is communicated from a subterranean well using a pipe, called a “production string.” The production string extends through a wellbore that is drilled through the producing formation and may include various valves for purposes of controlling the production of the hydrocarbon fluid. One such valve is a ball valve that may be operated for purposes of controlling the flow of the hydrocarbon fluid through the central passageway of the production string. Another valve that is typically part of a production string is a circulating valve, a valve that is operated to control the flow of the hydrocarbon fluid between the central passageway and the region outside of the string, called the “annulus.”
A well may be in an underbalanced state, a state in which the pressure that is exerted by the formation is greater than the hydrostatic pressure that is exerted by the fluid in the annulus. One type of circulating valve that is used in an underbalanced well has a series of check valve elements through which well fluid is circulated for purposes of opening and closing the valve. A potential challenge in using such a circulating valve is that typically, the central passageway of the production tubing string above the valve must be filled with fluid in order to properly operate the valve.
Another type of conventional circulating valve is remotely operated by communicating stimuli (pressure pulses, for example) into the fluid in the annulus near the valve. A sensor (a pressure sensor, for example) of the circulating valve detects the stimuli, and electromechanics of the valve typically decode commands from the stimuli and operate the valve accordingly. Although there is no requirement that the central passageway be filled with fluid for purposes of operating this type of circulating valve, the valve typically is not suitable for use in a high pressure high temperature (HPHT) environment due to temperature limitations of the valve.